Telegraph repeater



Jan. 19, 1926. I 1,569,899

G. S. VERNAM ET Al.-

TEFLEGRAPHIREPEATER Filed May 24, 1922 I N V EN TO RS 6; 6i @WEEEWZW/I/ BY V ATTORNEY Patented Jan. 19, 1926.

UNITED STATES,

1,569,899 PATENT OFFWE.

GILBERT S. VERNAM, 0F BROOKLYN, ANT) EDWARD IF. WATSON, 0F YONKERS, vNEW YORK, ASSIGNORS TO AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A COIL.

:PonA'rroN or NEW YORK.

TELEGRAPH nnrrm'rnn;

Application filed Kay 24, 1922. Serial No. 563,313.

To all whom it may concern:

Be it known that we, Ginnnn'r S. VERNAM and EDWARD .F. WA'rsoN, citizens of the United States, residing at Brooklyn and Yonkers, in the counties of Kings andlVestchester and State of New York, respectively, have invented certain Improvements in Telegraph Repeaters, of which the following is a s ecification.

TlllS invention relates to telegraph circuits and more particularly to the type of telegraph circuits in which signals are transmitted in but one direction over the same line at one time, although the system is so arranged that signals may be transmitted in either direction;

One of the objects of the invention is to provide an intermediate repeater station for circuits of the above type and to provide means whereby the intermediate station can send to both the terminal stations, can receive from either terminal station, and whereby signals from one terminal station, can be repeated through the intermediate station to the other terminal station. The invention also includes the provision of improved means whereby the operators at any of the stations may transmit break signals to each other. The intermediate repeater station of this invention is particularly adapted for use with a single Morse circuit of the type illustrated in a co-pending application, Serial No. 516,868, filed November 21, 1921, in the name of E. F. Watson, now become Patent No. 1,541,878, granted June 16, 1925 and hasbeen illustrated as associated with such a circuit specifically. However, it is understood that it is capable of embodiment in other types of single Morse lines. Other features and objects of the invention will appear more fully from the detailed description hereinafter given.

The. invention may be more fully understood from the following description, to gether with the accompanying drawing in which is illustrated a circuit diagram em bodying the features of the invention.

In the drawing are illustrated two terminal stations A and B interconnected by an intermediate repeater station C. ML and ML indicate sections of a transmission line connecting stations A and B with station C. At station A a local loop L extends to a subscribers station, in which suitable transmitting and receiving apparatus may provided; for example, a loop L is illustrated as including a schematically indicated transmitting distributor TD of a printing telegraph set and a home recording relay HER on such a set.

*The loop L at station A is balanced by means of a balancing circuit or resistance N, and windings of a polar pole changing relay PG and. a polar break release relay BER are included 1n the loop L and balancing circuit N. At the junction point between the loop L and the-balancing circuit N a connection extends to the armature of a polar receiving relay RR, which relay may, under certain conditions, be associated with a section ML of the main line for transmitting signals to the loop. The connection to the armature of the receiving relay may also include an auxiliary polar relay AR for athe main line ML to the armature of the pole changer PC includes the winding of a break relay BB. The break relay BR is a marginal neutral relay, so designed that it will be unresponsive to positive or negative vcurrents transmitted over the line in connection with ordinary signaling, but will be responsive to a current of greater amplitude transmitted over the line as a result of a break signal. The transfer relay TR has two windings, one of which is controlled by the armature of the break relay BR for initially energizing the transfer relay and the other of which is a locking winding controlled by a locking contact of the transfer relay.. The circuit of the locking winding is controlled by the armature oi the breakrelease relay BER and also by the armature of the auxiliary relay AR previously mentioned. p A

The apparatus at station 13 is identical with that at station A and corresponding elements are represented by the same reference characters primed. Further details of the apparatus will be clear from a description of the operation.

The main line sections ML and ML, which the armature of may be termed the west line and east line respectively, are connected to station C over the contacts of a cut-out relay COR. At station C are provided the west transfer relay VVTR and the east transfer relay ETR. There is also provided the west break relay WBR and the east break relay EBR. These break relays are neutral marginal relays and will not respond to the ordinary signaling currents but will res 0nd to currents of greater amplitude. T e west break relay and the east break relay are normally connected serially with the line sections ML and ML and with the windings of a home recording relay HRR Associated with the home recording relay is a circuit, including the windings of a pole changer relay PU and a break control relay BGR. This circuit may be controlled by a sending keyor sending distributor SD. There'is also provided a receiving relay RR a sender switch ing relay SSR and a break key BK The apparatus at station 0 will. be more readily understood from the following description of its operation.

The operation of the apparatus at the terminal stations A and B may be more readily understood by omitting the station C from the circuit and assumin that the line sections ML and ML are directl each other. Under these con itions the aparatus at stations A and B is illustrated as in condition for transmitting from station A to station B. Under these conditions, transfer relay TR at station B is locked up to connect the line ML to the receiving relay RR. At station A the transfer relay TR is deenergized so that the line ML is connected to the armature of the pole changer PG. When the transfer relay TR is deenergized a negative battery is connected from the back left-hand contact of the transfer relay to the winding ofthe receiving relay RR so that the armature of the latter relay is maintained against its negative contact. Under these conditions, when the loop L is closed the current flows from the positive battery through the winding of the ome recording relay HRR through the transmitting distributor TD, through the loo windings of the break release relay B R and pole changer PC and through the winding of the auxiliary relay AR over the contact of the receiving relay RR to negative battery. Current also flows froni ground through the balancing resistance N, balancing windings of the break release relay ERR and pole changer PC, through the winding of the auxiliary relay AR and over the contact of the receiving relay to negative battery. Obviously, the current flowing through the loop windings of the pole changer and the break release relay is substantially-twice as great as that flowing through the balancing windings, owing to the fact that the positive and connected to negative batteries are connected in series with respect to the loop circuit. The tendency of the current fiowin through the balancing windings is to shift the armature of the pole changer PG and the break release relay BRR to their upper contacts, but owing to the greater pull in the opposite direction due to the loop windings of said relays, the armatures are held to their lower contacts so that negative battery is connected through the winding of the break relay BR and over the right-hand back contact of the transfer relay to the main line section ML. The resultant line current flows over the front left-hand contact of the transfer relay TR at station B and through the winding of the receiving relay RR to ground. The armature of the receiving relay RR is therefore held against its negative contact and the current conditions in the loop circuit L are the same 'as described at station A, so that the armature of break release relay BRR is held against its lower contact, thereby maintaining a locking circuit through the left-hand winding and over the right-hand front contact of the transfer relay PR.

The conditions just described obtain during the transmission of marking signals. When a spacing signal is to be transmitted the loop L will be opened by means of the transmitting distributor TD at station A, so that no current flows through the loop windings of the pole changer PC and the break release relay BRR. The balancing windings of these relays now become efiective. The shifting of the armature of the break release relay is without effect but the armature of the pole changer PG connects positlve current to the main line ML so that the receiving re ay RR shifts its armature to the positive contact. The positive battery is now connected to both ends of the 100 L so that no current flows through the p windings of the pole changer PC, break release relay BRR and through the windings of the home recording relay HRR. Current flows through the balancing wind ings of the relays PC and BRR in the opposite direction so that these windings are now energized in such a direction as to tend to hold their armatures against their lower contacts. Consequently, the shifting of the battery connections by means of the relav RR is without effect upon the armatures of the pole changer PC and the break release relay BRR. The armature of the auxiliary relay AR is shifted to its upper contact tin provide an additional locking circuit for the left-hand winding of the transfer relay TR. The provision of the relay AR for this purpose is not strictly necessary, as the locking circuit will be provided over the armature of the break release relay BRR' but the provision of this additional locking circuit in sures against defective operation of the under the conditions just Consequently, when the relayHRR is deenergized by reason of the fact that positive battery is conncted to both ends of the loop during the first space signal of the group, the release of its armature will control the release of the receiving distributor in a well known manner.

If, while signals are being transmitted from station A, it is desired to transmit signals from station B, the loop circuit L may be opened, as, for example, by means of the break key BK. As soon as a negative or marking signal is received from station A,

negative battery will be connected to the loop over the left-hand contact of the receiv ing relay RR. As the loop windings of the pole changer PC and break release rclay BRR are deenergized, the balancing windings become effective to shift their armatures to the upper contacts. The shifting of the armature of the break release re lay BRR opens the locking circuit of the transfer relay TR, which is deenergized, so that its right-hand back contact connects negative battery to the receiving relay RR to hold the armature of the latter relay against its negative contact. At its lefthand back contact transfer relay TR connects the line ML through the winding of the break relay BR to the armature of the pole changer PC.

The armatureofthe pole changer is connected to positive battery at station B and it will-be remembered that the changes just described occur at the time a marking signal is being transmitted from station A, so that negative battery is connected to the line ML at the latter station. This results in a current flow of approximately twice the normal amplitude through the winding of the break relay BR over'the line sections ML and ML and through the winding of the break relay BR at station A. Both break relays are energized but the energization of the break relay BR at station l3- is without effect to energize the transfer relay TR, 0wing to the fact that the circuit of the latter relay is held open at the armature of the break release relay BBB and at the armature of the auxiliary relay AR. Consequently, the transfer relay TR at station B remains deenergized. At station A, however, the armature of the break release relay will be upon its lower contact, owing to the fact that the loop L is closed and upon the energization of the break relay BR a circuit is completed from ground, over the contact of the break release relay BRR, over the front contact of the rela'yBR and through the left-hand winding of the transfer relay TR to negative battery. The transfer relay TR is energized and at its left-hand contact completes a locking circuit through its right. hand winding. By means of its right-hand armature, said relay shifts the connection of the line ML from the control of the armature of the ole changer PC into circuit .with the receiving relay RR. Signals may now be transmitted from station B to station A in an obvious manner. In other words, we have a line circuit with terminal stations at each end thereof and each terminal station has transmitting and receiving apparatus thereat. There are also provided switching devices at each station for connecting a transmitting apparatus to the line at one station and a receiving apparatus to. the line at the second station, so that signaling currents may be transmitted over the line in one direction. Such switching devices also function to connect the transmitting apparatus to the line at the secondstation and the receiving apparatus to the line at the first station to transmit signaling cur-. rents in the opposite direction. These switching devices are controlled by means unresponsive to normal signaling currents but responsive to abnormal current conditions of the line.

The intermediate station repeater C is shown in the drawing in position for sending east and west, or in other words, to the stations B and A respectively. The signals at station C are initiated by the operation of a key or sending distributor SD. The operation of the distributor opens and closes the circuit of the break control relay BCR and the pole changer relay PC,. The operation of the pole changer relay causes positive and negative impulses to be sent to'the coils of the home record relay HRR where the current divides, one half going through the left noise killer impedance, west break relay l/VBR, back contact of the west transfer relay WTR, the line rheostat R and the left front contact of the repeatercut-ofi rel? COR to the west line ML. The other hal takesa similar path through the righthand noise killer impedance and the east pprtion of the apparatus to the east line Thus, the impulses from the intermediate stationare sent in both directions, these impulses being received at the distant stations bypolar relays, 'such as the relays RR and RR connected to ground. The distant stations may be terminal stations as shown or other intermediate station repeaters. The coils of the home record relay HRR are connected in parallel aiding so that the impulses passing through either or both of the coils will operate the relay. The

(ill

armature and contacts (not shown in the drawing) of this relay may operate a sounder or they may be connected into a printer circuit to act as a line relay. This means that the home record relay will act as the line relay for the interi'nediate station printer set and that all outgoing signals will be recorded on this printer. In case the operator at the west station, such as station A, should desire to send, it will be necessary for him to first break in the usual manner, causing the west transfer relay VTR and the sender switching relay SSH to be operated. A more detailed description of the breaking operation will be given later. The west line ML is then connected to ground through the receiving polar relay RR, so that the signals sent by the west station will be received by this polar rela The operation of the receiving relay Rft, opens and closes the pole changer circuit, causing positive and negative impulses to be sent through the right-hand coil of the home record relay HRR to the east line ML. The home record relay will operate the intermediate station printer set. The circuit through the left coil of the home record relay to the west line ML is open at. the left back contact of its transfer relay WTR.

If the operator at the east station should, desire to send it will be necessary for him to break in the usual manner. This will cause the east tranfer relay ETR and the sender switching relay SSE to be operated and the polar receiving relay RR will then be connected to the east line ML. Signals from the east station, such as station B, will then operate the receiving relay RR, and the pole changer relay PC thus repeating the signals through the left-hand coil of the home record relay HRR to the west line ML.

The breaking arrangement for each side of the intermediate repeater set operate on the same general principle as the breaking arrangements for the terminal sets which have been heretofore described. At the intermediate station C, however, there are three different conditions under which breaking occurs. These conditions are as follows: Onedistant station breaking the intermediate station, one distant station breaking the other distant station through the intermediate set, and the intermediate station breaking a distant station. The operation of the arrangements under these three conditions will now be described.

lVhen the intermediate station C is transmitting signals to the terminal stations and when one distant station, taking, for example, the west one, such as station A, desires to stop or break the intermediate stations sending, the operator at the west station will, open his break key and send out a positive impulse. This positive impulse, meeting the next negative one from the interme diate station, will cause double current to flow in the west line ML. This double current will operate the west break relay WBR,

thus closing the following circuit; from negative battery through the winding of the sender switchin relay SSH, left front contact of the brea k control relay BGR, front. contact of the west break relay 7BR, winding of the west transfer relay \V'llt, left back contact of the east transfer relay ETR and break key BK to positive battery. The sender switching relay SSR and the west transfer relay \VTR will now operate, the west transfer relay'lVTR locking iii-by means of its right front contact through the winding of the sender switching relay SSH, a back contact of the east transfer relay ETR and the break key BK,. The sender switching relay short-circuits the sending distributor SD and connects the armature and contact of the receiving relay RR, in series with the ole chan er circuit. The west line BIL will now be isconnectedfrom the sending pole changer PC, and connected to the receiving relay RR by the operation of the west transfer relay WTR. The spacing or break impulse from the west station, such as station A, will cause the armature of the receiving relay 'RR, to open the pole changer circuit so that a spacing signal will be repeated to the east line ML, the home record relay HRR sending an open signal into the printer set which will operate the printer break relay or otherwise stop the sending. This spacing signal will continue to be received until the west stations break key is closed. The circuit will now be in position for sending from the west station. A'similar operation takes place when the east station breaks the intermediate set.

\Vith the west station, such as station A, sending. the east station, such as station B. may break by sending out a spacing signal in the usual manner which will operate the east break relay EBR when a marking impulse is sent over the east line. The cast break relay EBR in operating closes the following circuit: from positive battery through the break key BIL. right front contact of break control relay B(-ll, front contact of east break relay ERR. winding of east transfer relay Ellipback contact of west break relay \VBR. left front contact of break control relay BCR. winding of sender switching relay SSR to negative battery: The simultaneous operation of the east break and transfer relays opens the locking circuit of the west transfer relay, thus releasing it so that the west line ML will be connected to the sending pole changer PC,. The sender switching relay SSR will remain operated in series with the locking circuit of the east transfer relay ETR. The

7 station.

operation of the east transfer relay disconnects the east sending apparatus and con- .nects the receiving relay RR, to the east.

line ML. The spacing impulse from the east station will .cause the receivin RR, to open the circuit of the polg l hanger so that it will send a spacing si al over the west line ML. This causes a break signal to be sent to the west station, operating the break relay BR at that station and the west break relay VVBR at the intermediate station. The west transfer relay lVTR at the intermediate station will not operate at this time, as its operating circuit is open at the left front contacts of the break control relay BCR, owing to the fact that the pole changer circuit is open. The operation of the transfer relay TR at the west station will put the system in osition so that signals from the east station, such as station B, will be received at the intermediate station 0 and repeated to the west station, such as station A. In case station A should break station B, the operation would be correspondingly the same.

Let it be assumed, now, tion, such as station B, is sending and that the intermediate station C wishes to send. The intermediate station operator will open his break ke BK releasing the east transfer relay E R and the sender switching relay SSR and at the same time opening the polechan er circuit so that a spacing 1mpulse will e sent out. This spacing signal, meeting a marking impulse from station 13, will operate the break relay BR at station '13 and the east break relay EBB at the intermediate station. The operation of the break relay at station B places that station in position to receive while at the interme V diate station nothing happens as the circuit through the east transfer relay ETR is open at the front contact of the break control relay BCR and at the break key BK,. As the west station, such as station A, had been receiving before the intermediate, station broke, no other action than the receipt of a spacin signal will take place at that station. Thus, after the break key BK has been closed the intermediate set may start to send. The operation would have been similar had station A been sending and the intermediate station desired to break said It is ointed out that the sender switch relay S R operates in series with either of the transfer relays WTR and ETR and short-circuits the sending apparatus. Gonsequently, the intermediate station operator must always operate his break key BK before he can send, provided that he has previously been receiving. This prevents the operator from sending out in only one direction as would be the case had he neglected to first break. The sender switching relay bodiinent in many an that the east sta- Vhile the arrangements of the invention,

have been disclosed in certain specific arrangements which are deemed desirable it is understood that the are capable of emd other widely varied forms without departing from the spirit of the invention as defined in the appended claims. \Vhat is claimed is: 1. In a signaling system, a line circuit, a repeater station associated with said line circuit and terminal stations associated with each end of said line circuit, transmitting apparatus and reteiving apparatus at each terminal station, a pole changer transmitter and a polar receiving relay at said repeater station, an operating circuitfor said pole changer transmitter controlled over the con tacts-of said polar receiving relay, and

switching means at said repeaterstation terminal station, a pole changer transmitter and a polar receiving relay at said repeater station, an operating circuit for said pole changer transmitter controlled over the contactsof said polar receiving relay, switching means at said repeater station whereby said polar receiving relay may be connected to either section of said line and said pole changer transmitter ma be connected to the other section of said inc, and means unresponsive to normal signaling currents but responsive to abnormal current conditions of the line for controlling said switching means.

3. In a signaling system, a line circuit, a repeater station associated with said line circuit andv terminal stations associated with each end of said line circuit, transmitting apparatus at said'repeater station, sending means for controlling said repeater transmitting apparatus, receiving apparatus at said repeater station, means for o ratively connecting said repeater transmitting appaconnecting one of said line sections from said repeater transmittin apparatus and connecting said line section to said repeater receiving apparatus.

4. In a signaling system, a line circuit, a repeater station associated with said line circuit and terminal stations associated with each end of said line circuit, transmitting and receiving apparatus at each terminal station, transmitting apparatus at said repeater station, sending means for controlling said repeater transmitting apparatus, receiving apparatus at said repeater station, means for operatively connecting said repeater transmitting apparatus to both of the sections of said line at the same time, switching means for disconnecting one of said line sec.- tions from said repeater transmitting apparatus and connecting said line section to said repeater receiving apparatus, and means controlled by said last mentioned means whereby control over said repeater transmitting apparatus may be transferred "from said sending means to said repeater receiving apparatus.

5. In a signaling system, a line circuit, a repeater station associated with said line circuit and terminal stations associated with each end of said line circuit. said repeater station comprising a pole changer transmitter common to both of the sections of said line, a polar receiving relay, means for controlling said pole changer by said receiving relay, and switching means controllable from either terminal station for connecting said receiving relay to either line section and said pole changer to the other line section.

6. In a signaling system, a line circuit, a repeater station associated with said line circuit and terminal stations associated with each end of said line circuit, said repeater station comprising a transmitting device common to both of the sections of said line, a source of current for said transmitting device, a receiving device, means for controlling said transmitting device by said receiving device, switching means controllable from either terminal station for connecting said receiving device to either line section and said transmitting device to the other line section, and a cut-off relay for connecting said line sections to said repeater station, said relay being normally energized from said source of current for said repeater transmitting device and an auxiliary circuit closed upon the deenergization of said cutoff relay for connecting said line sections directly together.

7. In a signaling system, a line circuit, a repeater station associated with said line circuit and terminal stations associated with each end of said line circuit, transmitting apparatus at said repeater station, sending means for controlling saidrepeater transmitting apparatus. receiving apparatus at said repeater station, means for normally operatively connecting said repeater transmitting appa 'atus to both of the sections of said line at the same time, switching means for disconnecting one of said line sections from said repeater transmitting apparatus and connecting said line section to said repeater receiving apparatus, and a break key at said repeater station for restoring said switching means to normal whereby said transmitting apparatus may again be connected to-both of said line sections.

In testimony whereof. we have signed our names to this specification this 22nd day of May, 1922.

GILBERT S. VERNAM. EDWARD F. WATSON. 

